FIG. 2 shows a conventional example of a wiring harness installation structure. The wiring harness installation structure shown herein is an installing construction for installing a wiring harness W so as to extend from an engine compartment 3, which constitutes an area external to a vehicle compartment 1, into an interior of the vehicle compartment 1.
A grommet made of a rubber material is fittingly mounted in a harness insertion hole 9. The harness insertion hole 9 is formed so as to penetrate through a body panel (a dash panel) 7 which is provided between the engine compartment 3 and the vehicle compartment 1 so as to separate the interior and exterior of the vehicle compartment 1. A protector 13 is installed at every key point in a harness installation path as required within the engine compartment 3, which constitutes the area external to the vehicle compartment 1.
The grommet 11 has such a configuration that the wiring harness W is inserted through a center of a cylindrical structure which is fittingly held in the harness insertion hole 9 which is formed so as to penetrate through the body panel 7. Therefore, the wiring harness W which is inserted through the harness insertion hole 9 is prevented from a direct contact with a circumferential edge of the harness insertion hole 9, which would otherwise damage the wiring harness W.
The protector 13 is a cylindrical structure for accommodating the wiring harness W for protection within the engine compartment 3 and is formed of a hard resin material, for example. The protector 13 is equipped for the purpose of preventing the wiring harness W from being subjected to water, as well as preventing the wiring harness W from being damaged through interference with a peripheral device or structure.
Normally, as is shown in the figure, the protector 13 is disposed only an appropriate distance apart from the body panel 7, and the wiring harness W is exposed between the grommet 11 and the protector 13.
Incidentally, there is a possibility that drips of water resulting from rain water or washing water infiltrates the engine compartment 3 from the outside thereof. There is a possibility that the wiring harness W exposed within the engine compartment 3 is subjected to drips of water intruded in the interior of the engine compartment 3.
Then, in order to prevent drips of water caught on the exposed portion of the wiring harness W in proximity to the grommet 11 from running through gaps defined between a large number of electric wires which makes up the wiring harness W to intrude the vehicle compartment 1 side, conventionally, a waterproofing treatment is implemented for injecting a water stop agent 15 into an interior of the grommet 11 (for example, Patent Document 1).
The water stop agent 15 is initially in a liquid condition and is injected into the gaps defined between the electric wires which are inserted through the grommet 11 to set after a predetermined time elapses, so that the gaps between the electric wires are sealed watertight, whereby even in case the wiring harness W exposed within the engine compartment 3 catches some of the drips of water, water so caught is prevented from running through the gaps between the electric wires to infiltrate the vehicle compartment 1 side.    Patent Document 1: JP-A-11-89045